SMAD6 variants in craniosynostosis: genotype and phenotype evaluation

Purpose: Enrichment of heterozygous missense and truncating SMAD6 variants was previously reported in nonsyndromic sagittal and metopic synostosis, and interaction of SMAD6 variants with a common polymorphism near BMP2 (rs1884302) was proposed to contribute to inconsistent penetrance. We determined the occurrence of SMAD6 variants in all types of craniosynostosis, evaluated the impact of different missense variants on SMAD6 function, and tested independently whether rs1884302 genotype significantl

The neurogenic effects of exogenous neuropeptide Y: early molecular events and long-lasting effects in the hippocampus of trimethyltin-treated rats.

Modulation of endogenous neurogenesis is regarded as a promising challenge in neuroprotection. In the rat model of hippocampal neurodegeneration obtained by Trimethyltin (TMT) administration (8 mg/kg), characterised by selective pyramidal cell loss, enhanced neurogenesis, seizures and cognitive impairment, we previously demonstrated a proliferative role of exogenous neuropeptide Y (NPY), on dentate progenitors in the early phases of neurodegeneration. To investigate the functional integration of newly-born neurons, here we studied in adult rats the long-term effects of intracerebroventricular administration of NPY (2 \ub5g/2 \ub5l, 4 days after TMT-treatment), which plays an adjuvant role in neurodegeneration and epilepsy. Our results indicate that 30 days after NPY administration the number of new neurons was still higher in TMT+NPY-treated rats than in control+saline group. As a functional correlate of the integration of new neurons into the hippocampal network, long-term potentiation recorded in Dentate Gyrus (DG) in the absence of GABAA receptor blockade was higher in the TMT+NPY-treated group than in all other groups. Furthermore, qPCR analysis of Kruppel-like factor 9, a transcription factor essential for late-phase maturation of neurons in the DG, and of the cyclin-dependent kinase 5, critically involved in the maturation and dendrite extension of newly-born neurons, revealed a significant up-regulation of both genes in TMT+NPY-treated rats compared with all other groups. To explore the early molecular events activated by NPY administration, the Sonic Hedgehog (Shh) signalling pathway, which participates in the maintenance of the neurogenic hippocampal niche, was evaluated by qPCR 1, 3 and 5 days after NPY-treatment. An early significant up-regulation of Shh expression was detected in TMT+NPY-treated rats compared with all other groups, associated with a modulation of downstream genes. Our data indicate that the neurogenic effect of NPY administration during TMT-induced neurodegeneration involves early Shh pathway activation and results in a functional integration of newly-generated neurons into the local circuit

Hypoxia-like transcriptional activation in TMT-induced degeneration: microarray expression analysis on PC12 cells

To more clearly elucidate the complete network of molecular mechanisms induced by trimethyltin (TMT) toxicity, we used a homogeneous cell culture model represented by PC12 cells treated with 1 and 5 micromol/L TMT for 24 h. The gene expression profile was performed by microarray analysis, enabling us to identify 189 genes that were significantly modulated in treated cells, compared with controls. The main effects of TMT on gene expression seem to be related to the activation of metabolic processes (glycolysis and lipogenesis) along with cell death pathways, membrane remodeling and intracellular biomolecules trafficking. These alterations are triggered by the neurotoxicant earlier than a strong decrease in cell viability, which occurs at higher TMT concentrations or at later time points. Some aspects of the transcriptional modulation observed in this study resemble the gene activation known to occur during cell response to hypoxia. Other cell toxicants have also been reported to exert similar effects on gene expression. Therefore, our data help to delineate general basic adaptive mechanisms possibly shared by cells responding to different death-inducing noxae, such as TMT

Correction: SMAD6 variants in craniosynostosis: genotype and phenotype evaluation (Genetics in Medicine, (2020), 10.1038/s41436-020-0817-2)

The version of the Article previously published did not acknowledge Freya Boardman-Pretty17,18 and the Genomics England Research Consortium in the author list. This has now been corrected in both the PDF and HTML versions of the Article

Gene expression profiling in human craniosynostoses: a tool to investigate the molecular basis of suture ossification

Non-sy ndromic craniosy nostoses (NSC) occur as isolated skull malf ormations due to the premature ossif ication of one (single suture f orms) or more (complex f orms) calv arial sutures and represent the most f requent f orm of craniosy nostosis worldwide. The etiology of NSC is still largely unknown, as a genetic basis can be rarely demonstrated especially in single-suture f orms. In these cases, during the prenatal/perinatal dev elopment of af f ected patients, only one suture undergoes a premature direct ossif ication within an otherwise phy siologically grown skull. This could suggest that def inite somatic alterations, possibly due to unclear env ironmental agents, occur locally at the site of premature suture f usion during skull dev elopment. A promising tool to inv estigate the molecular mechanisms that may orchestrate this ev ent is the comparativ e analy sis of suture- and sy nostosis-deriv ed tissues and cells. Particularly , this rev iew will f ocus on the dif f erent studies that attempted to clarif y this issue using genome-wide microarray -based technologies f or the comparativ e analy sis of gene expression prof iles. All relev ant results will be comprehensiv ely rev iewed, possibly compared and critically discussed